Lifejackets are worn in a number of applications, to provide buoyancy to the person who is wearing the lifejacket. For example, a lifejacket may be worn by a person engaged in water sports or by a person travelling by sea, either for the duration of the journey or in the event of an emergency. The buoyancy of a lifejacket is provided by a material of low density, such as pockets of air or blocks of expanded polystyrene. For a lifejacket to provide sufficient buoyancy, the lifejacket needs to contain a sufficient volume of buoyant material which inevitably makes the lifejacket bulky. This bulkiness can hinder movement of the person wearing the lifejacket. Therefore, it is common to use inflatable lifejackets which are compact when deflated and which can be inflated when required. Similarly, it is known to provide inflatable liferafts which can be stored on-deck and inflated as they are thrown overboard.
An example of an inflatable lifejacket is shown in FIG. 1. The lifejacket 101 comprises a fabric outer skin 103 and an inner inflatable tube 105. The fabric outer skin 103 is folded to form a front panel 107 and a back panel 109 which are detachably joined around the outer peripheral edge 111 of the lifejacket 101 by a hook-and-loop surface fastener 113, 115 (see insert). This forms a compact, relatively thin article which can be worn without hindering the movement of the user.
When the lifejacket 101 is deployed, a canister of compressed gas (not shown) is triggered by pulling a cord 117 to inflate the inner tube 105 of the lifejacket 101. As the inner tube 105 inflates, it pushes against the front panel 107 and the back panel 109 of the outer skin 103, to force open the surface fastener 113, 115 which runs around the peripheral edge 111 of the lifejacket 101. After a few seconds the inner tube 105 is fully inflated, the surface fastener 113, 115 is open all the way along its length and the inflated inner tube 105 projects beyond the peripheral edge 111 of the lifejacket 101.
A disadvantage of using a hook-and-loop surface fastener to detachably join the front panel 107 and back panel 109 of the outer skin 103 is that each time the inner tube 105 is inflated and the hook-and-loop surface fastener 113, 115 is separated, the adhesive force between the two surface fasteners 113, 115 decreases as a result of wear and tear on the hooks and loops. Furthermore, as such lifejackets 101 are generally used in a marine environment, the hook-and-loop surface fastener often come into contact with water which can degrade the materials from which the surface fastener is made, thereby reducing the effectiveness of the hook-and-loop surface fastener over an extended period of time, requiring periodic replacement of the surface fastener.
A further disadvantage of using a surface fastener for this application is the danger which may occur when such lifejackets are used in freezing conditions where there is a possibility that water, which has sprayed onto the lifejacket, may freeze. If water freezes in the join of the surface fastener then this will prevent separation of the two surfaces. These disadvantages can be overcome if the hook-and-loop surface fastener is replaced by a slide fastener, such as a zip fastener. However, the surface fastener cannot be simply replaced by a conventional slide fastener, as conventional slide fasteners cannot be burst open at a point along their length, unlike the way in which the surface fastener operates in a lifejacket.